A chronic expanding hematoma in the thoracic cavity is very rare and is clinically included in a category of chronic hemorrhagic empyemas as a special type of chronic empyemas in Japan. In this paper, we report a case of this disease. The patient was a 69-year-old female, who was underwent bilateral artificial pneumothorax for pulmonary tuberculosis 35 years ago. On 25. Nov. 1996, she admitted into Nagoya University Hospital for a diagnosis of intrathoracic tumor. On 2. Dec. 1996, we removed the tumor with combined resection of left lower lobe. The tumor was diagnosed pathologically as an intrathoracic chronic expanding hematoma. This disease is benign, but progressive clinically. In progressive case it is dangerous to remove the tumor for a risk of excessive bleeding and hard adhesion to the chest wall. So we think the earlier is a surgical treatment, the better is a management for this disease.